Pawl and ratchet mechanism for adjusting gap between male and female cable sheathing dies



Apnl 5, 1960 P. BILLEN 2,931,498

PAWL AND RATCHET MECHANISM FOR ADJUSTING GAP BETWEEN MALE AND FEMALE CABLE SHEATHING DIES Filed June 3, 1957 4 Sheets-Sheet 1 I wvnvron Pfi z) 6630/ April 5, 1960 P BILLEN 2,931,498

PAWL AND RATCHEZT MECHANISM FOR ADJUS G GAP BETWEEN MALE AND FEMALE CABLE SHEATH DIES Filed June 3, 1957 4 Sheets-Sheet 2 /NVEN 7'07? P131; Z/ZQIZ/ Aprll 5, 1960 P. BILLEN 2,931,498

PAWL AND RATCHET MECHANISM FOR ADJUSTING GAP BETWEEN MALE AND FEMALE CABLE SHEATHING DIES Filed June 3, 1957 4 Sheets-Sheet 3 Fly. 5

RB z'JLlezz/ Apnl 5, 1960 P. BILLEN 2,931,498

PAWL AND RATCHET MECHANISM FOR ADJUSTING GAP BETWEEN MALE AND FEMALE CABLE SHEATHING DIES Filed June 3, 1957 4 Sheets-Sheet 4 INVENTOE United States atent' PAWL AND RAT CHET MECHANISM FOR ADJUST- ING GAP BETWEEN MALE AND FEMALE CABLE SHEATHING DIES Peter Billen, Leverkusen-Kuppersteg, Germany, assignor' to Schloemann Aktiengesellschaft, Dusseldorf, Germany The invention relates to a tube extrusion or cable sheathing press. During operation the fine adjustment of the annular gap between mandrel and die is effected in such presses by adjustment of the position of the mandrel. The fine adjustment of aluminium extrusion presses during operation is therefore usually impossible and in lead extrusion presses it is difficult to perform because the mandrel which projects into the extrusion chamber is generally exposed to considerable lateral pressures which are not self-compensatory and therefore subject the mandrel to a heavy unilateral load. This applies more particularly to presses which have only one receiver which is arranged at right angles to the axis of the press. displacement of the mandrel must therefore overcome considerable wall friction which may frequently be large enough to prevent the mandrel from being moved during operation at all so that the pressure obtaining in the extrusion chamber must be reduced before any adjustment can be effected. A fine adjustment devices-an certainly not be used during operation to adjust the width of the extrusion gap for the compensation of variations resulting from the breathing of the receiver when the pressure of the ram increases or decreases.

It is the object of the present invention to provide a form of construction which will permit the Width of the gap between the mandrel and the die to be varied and fine adjusted at any time during actual operation of the press. The invention relates to a tube extrusion or. cable sheathing press comprising means for the fine adjustment of the annular gap between the mandrel and the die during operation of the press, the invention consisting in that fine adjustment is effected by moving the die or die holder which is arranged outside the extrusion chamber in a bore in the'receiver of the press. The means for the fine adjustment of the position of the die can, of course, be operated in dependence upon the pressure obtaining in the receiver or container bore, or upon the pressure on the working piston of the press. Automatic control may then be adapted to increase the gap between mandrel and die shortly before the end of each extrusion before the press is stopped. As soon as a fresh billet has been inserted and the ram commences another forward stroke, the width of the gap is arranged to be reduced again. In the region of the much feared bamboo rings this prevents the formation of a short neck in the cable sheath which is thinner than'the normal cable diameter, the described method of control actually tending to thicken this section and to compensate any'wea'kness in the structure of the material in the region of the bamboo rings by increasing the cross section of the sheath material.

A particularly suitable type of fine adjustment for the purpose of the present invention is one in whichthe die holder is rotatably and thus displaceably held in a threaded bore of the receiver and connected longitudinally displaceably but non-rotatably with a hollow shaft which can be rotated but not axially displaced with respect to the receiver and which is-provided-with means for rotat- Axial ing the same. Among other factors this form of con- ,struction has the advantage that a removal of the die and its replacement by a fresh die does not require the removalof any part of the fine adjustment device.

-The invention will be hereinafter more particularly described with reference to an illustrative embodiment thereof shown in the accompanying drawings in which:

Figure 1 is a cross section of a receiver and of the pressing tools contrived as proposed by the invention, the section being taken on the line Ii in Figure 4,

Figure 2 is a view in the direction lie-ll in Figure 1,

Figure 3 shows the parts illustrated in Figure 2 and the actuating means, but on. a reduced scale,

Figure 4, likewise on a reduced scale, is a section on the line IV-IV in Figure 1 with associated parts of the press,

Figure 5 is a section taken on the line VV in Figure 4, and

Figure 6 shows in greater detail the means for adjusting the position of the die by means of the varying pressure in the main extrusion cylinder.

The extrusion head 1 of the press is rigidly connected by tension rods 39 and nuts 31 with a main hydraulic cylinder 32 which has an opening 33 through which a pressure medium can be admitted and withdrawn. The cylinder 32 contains a slidably displaceable main piston 34 with a ram 35. The ram enters a container bore 36 in the extrusion head 1 of the press, the said bore communicating through. a channel 3'7 with the extrusion chamber 2 in the extrusion head. if the bore 36 contains a material such as aluminium the ram will squeeze it through channel. 37 into the extrusion chamber 2 when the piston 34 and the ram 35 are forced down by a pressure medium.

instead of only one container bore 36 in the extrusion head 1 of the press two such container bores 36 and 36a may be provided, communicating with the extrusion chamber 2 through channels 37 and 37a respectively. A piston 34a corresponding with the piston 34, and reciproeating in a second main cylinder (not shown) analogous to the cylinder 32, will then be provided, to squeeze material for extrusion into the extrusion chamber through the channel 37a by means of a ram 356: analogous to the ram 35. The general disposition may then be such that the two rams 35 and 35a perform their working strokes either simultaneously or alternately. A hollow mandrel-holder 3 carrying a mandrel 4 projects into the extrusion chamber 2. The opposite side of the extrusion chamber 2 opens into a cylindrical bore 5 in which a die 6 held by die holder '7 can be longitudinally displaced. The die holder 7 is screwed into a thread 7a in the cylindrical bore 5 and its projecting end is fitted with a longitudinal key member 3. The end is embraced by a hollow shaft 9 adapted to rotate in a hearing it? in a member 11 which prevents'the said shaft from being axially displaced in that it is rigidly connected with the extrusion head 1 of the press. internal diameter of the hollow shaft 9 is sufficient to permit the die holder 7 and the'die 6 axially to move therein. In other words, rotation of the hollow shaft 9 causes the die holder 7 to be moved forwards or backwards. The hollow shaft 9{ has two sets of annularly disposed ratchet teeth 12 and 13. Each of these rings of teeth can be engaged by a pawl 14 and 15 respectively. Both pawls pivot on a pin 16 secured to a double ring 1'7, which in turn is rotatably mounted on the hollow shaft 9. At one end the double ring 17 has a lever arm 18 with a slot 20 for a sliding block 21 rotatably mounted on the piston rod 22 of a piston 23 which is arranged to reciprocate in a cylinder 24. One of the pawls 14 or 15 must be disengaged when it is desired to adjust the die holder 7. Figures 2 and 3'show pawl 14 The in the disengaged position. It will be noted that in this position pawl 14, biased downwardly by gravity, will ride over teeth 12, whereas pawl 15, also held down by gravity, will engage the operating faces of teeth 13 to rotate the hollow shaft 9 and hence the die 6 in short steps as the piston 23 reciprocates. Alternatively, if pawl 14 is brought into engagement into position Mr: and pawl 15 is disengaged, the reciprocation of piston 23 will intermittently rotate the hollow shaft 9 and the die 6 in the opposite sense of rotation. By this means the width of the annular gap between the mandrel 4 and the die 6 will be altered. Two pressure pipes 26 and 26a and two relief pipes 27, 2742 are connected with cylinder 24. By suitable control means of known construction incorporated in the pipe lines 26, 26a, 27. and

27a a reciprocating movement is imparted to piston 23."

Control means may now be provided which control the operation of the piston 23 in. dependence upon the pressure inside the pressure chamber of the main cylinder 32 or of the two main cylinders. Engagement and disengagement of the pawls 14 and 15 may then likewise be automatically efiected in dependence upon the pressure in the main working cylinder or cylinders, so that the fine adjustment of the position of the die 6 will be automatically accomplished in conformity with the said pressure.

Figure 6 illustrates the fine adjustment of the die 6 in dependence upon the pressure in the main hydraulic cylinder 32. The breadth of the gap between the die 6 and the mandrel 4 is to be increased shortly before the end of each extrusion stroke, that is, upon a fall of pressure in the cylinder 32, and to be diminished shortly after the commencement of each forward stroke, that is to say, upon the pressure in the cylinder rising again. To obtain these small variations in the breadth of the gap, the piston 23 is moved to and fro in the cylinder 24, for the purpose of controlling the two pawls 14 and 15, so that the piston 23, in its outward stroke, increases the gap by a small amount, and in its return stroke reduces it again by the same amount.

From a pressure-liquid pipe 40 liquid under pressure has access by way of valves 41 and 42 to the inlet pipes 26 and 26a of the cylinder 24. The valves 41 and 42 are closed by springs 43 and 44, which bear against casings 45 and 45 respectively. The valve rods of the valves carry magnet cores 47 and 48, which can be moved by magnet coils 49 and 50 respectively in the direction for opening the valves. The magnet coils 49 and 50 are each connected by one endto electric current conductors 51 and by the other end to conductors 52 and 53 respectively. "From the conductor 52 a branch conductor 52:: leads to a magnet coil 54, which, by means of a magnet core 55, can open a valve 56, to connect the exhaust pipe 27a with a Waste-water pipe 57. In the same manner, by means of a magnet 59, similar to the magnet 54, 55, a valve 58 can be opened, against the action of a spring 60, when the magnet 59 receives current through a branch conductor 530 connected with the conductor 53.

The conductors 53 and 53a are connected to a contact bar 61, while the conductors 52 and 52a are connected to another contact bar 62. The contact bars 61 and as can receive current alternatively by way of a contact lever 63 controlled by a pressure gauge 64, which is connected by way of a pipe 330: to the inlet 33 through which pressure liquid is admitted to the cylinder 32, as shown in Figure 4. When there is no pressure prevailing in the cylinder 32, the lever 63 assumes the position shown in Figure 6. When pressure liquid enters and the pressure increases, the lever 63 turns in a clockwise direction, Until the lever 63 leaves the bar 62, current flows to the magnets 54, 55 and 47, 49, so that the valves 41 and 56 are open. Consequently the piston 23 is impelled into its extreme right-hand position, and the gap between the die 6 and the mandrel 4 is comparatively large. When the contact lever 63 leaves the V '4 contact bar 62, upon an increase of pressure in the cylinder 32 and in the pressure gauge 64, the valves 41 and 56 close automatically, owing to the magnets 54, 55 and 47, 49 no longer resisting the thrust of the springs acting upon them. When the pressure in the cylinder 32 and in the pressure gauge 64 increases further the contact bar 61 receives current from the contact lever 63, as a result of which, by Way of the conductors 53 and 53a, the magnets 59 and 48, 50 receive current, and the valves 58 and 42 are opened. The pressure liquid fiOWing from the pressure pipe 49 now pushes the piston 23 towards the left, the liquid located to the left of the piston passing through the exhaust valve 58 to the discharge pipe 57. The lever arm 18 is thus rocked in a clockwise direction, and consequently turns'the dieholder 7 in its screw thread 7a in such a way that the gap between the die 6 and the mandrel 4 is diminished. When upon a reduction of pressure in the cyilnder 32 the contact lever 63 rocks back again on to the contact bar 62, the lever arm 13 ,will return to the position shown, and will thereby enlarge the gap between the die and the mandrel again.

I claim:

1. A tube-extrusion or cable-sheathing press, comprising: an extrusion head formed with a screw-threaded bore, an externally screw-threaded die-holder engaging the thread in the said bore, a tubular die held by the said die-holder, a mandrel-holder mounted axially with the die and undisplaceably in the extrusion head, a mandrel held by the mandrel-holder, a ratchet-and-pawl mechanism mounted on said die-holder for rotating the die-holder relatively to the extrusion head, to thereby selectively shift the die axially relatively to the mandrel, and pressure operated means to actuate said ratchet-andpawl mechanism. 2. A press as claimed in claim 1, further comprising a second ratchet-and-pawl forming part of said ratchetand-pawl mechanism for selectively rotating thedieholder in the direction opposite to that in which it is rotated by the first-mentioned ratchet-and-pawl mechanism.

3. A tube-extrusion or cable-sheathing press, comprising: an extrusion head formed with a screw-threaded bore, an externally screw-threaded die-holder engaging the thread in the said bore, a tubular die held by the said die-holder, a mandrel-holder mounted axially with the die and undisplaceably in the extrusion head, a mandrel held by .the mandrel-holder, a rotatably mounted hollow shaft within which one end of the die-holder engages, means permitting relative axial motion-but preventing relative rotary motion between the die-holder and the hollow shaft, a ring of ratchet teeth on the hollow shaft, a movable pawl carrier mounted on said press adjacent said ratchet a pawl adapted to engage the said teeth mounted on said pawl carrier, and means for reciprocating the said pawl carrier with respect to said teeth so as to rotate the die-holder relatively to the extrusion head, and thereby shift the die axially relatively to the mandrel.

4. A press as claimed in claim 3, further comprising:

a second ring of ratchet teeth on the hollow shaft, the

teeth of this second ring being directed oppositely to those of the first-mentioned ring, a second pawl adapted to engage the teeth of the second ring mounted on said pawl carrier, the two pawls being engageable with their respective associated rings of teeth, and'means for reciprocating the pawls so as to rotate the die-holder selectively in either direction relatively to the extrusion head, and thereby shift the die axially towards or away from the mandrel as required.

5. A press as claimed in claim 3, in which said pawl carrier comprises: a ring rotatably mounted on said hollow shaft, the pawl that engages the ratchet teeth being pivotally mounted on the said ring, and a lever extending from and rigidly secured-to said ring, by means of which the ring can be turned about the axis of said hollow shaft through an angle, the means for reciprocating the said lever including a hydraulic cylinder and piston engaging the said lever.

6. A press as claimed in claim 4, in which said pawl carrier comprises: a ring rotatably mounted on said hollow shaft, the pawls that engage the ratchet teeth being pivotally mounted on the said ring, and a lever by means of which the ring can be turned through an angle, the means for reciprocating the pawls including a hydraulic cylinder and piston engaging the said lever.

7. A press as claimed in claim 6, the extrusion head being formed with an extrusion chamber in which the mandrel is located and with a container bore communieating with the said extrusion chamber, and the press further comprising: a ram reciprocable in the container bore, a main hydraulic piston for actuating the ram, and

a main hydraulic cylinder in which the said piston re- A References Cited in the file of this patent UNITED STATES PATENTS 399,291 Siemens Mar. 12, 1889 572,546 Johnson Dec. 8, 1896 1,167,626 Clarernont et a1 Jan. 11, 1916 FOREIGN PATENTS 27,693 Norway Mar. 5, 1917 r 380,037 Great Britain Sept. 8, 1932 r 876,573 France Aug. 10, 

